1. Field of the Invention
The present invention is directed to an x-ray diagnostics installation of the type having a primary radiation diaphragm disposed in the beam path of an x-ray tube, and control means for setting the position of the primary radiation diaphragm.
2. Description of the Prior Art
In x-ray diagnostics systems which result in the production of an x-ray image and/or a visible image corresponding to the x-ray image, the position of the primary radiation diaphragm, or the position of beam-interacting elements thereof, is adjustable for various purposes, such as for selecting the contour of the examination region which will appear in the image. For example, a heart contour diaphragm can be used in a so-called depth diaphragm top achieve a primary reduction in the contrast between the mediastinum (heart shadow) and the adjoining lung field for improving the image quality or for avoiding halations (glare) in the video image. The diaphragm can be adjusted to produce a straight contour, concave or convex shapes, or a wedge shape.
A primary radiation diaphragm of this type is disclosed in German Patent 1 800 879 for use in an x-ray exanination apparatus, wherein two lamellae can be moved toward and away from each other by actuating keys. The lamellae are mounted on a rotatable carrier, which can be rotated by means of a further operating key. The respective keys which control these different movements are identical, so that mistakes can easily occur.
More recently, a joystick has been predominantly used to control the operation of the primary radiation diaphragm as described, for example, in the brochure for the "ANGIOSTAR.RTM.", manufactured by Siemens AG. Pivoting the joystick toward the right or the left respectively causes an introduction of the diaphragm plates into the image, or a withdrawal of the diaphragm plates from the image. Movement of the joystick toward the front or rear results in a rotation of the entire diaphragm. Such operation of the joystick, however, is not ergonometric, and mistakes again can easily occur.